The proposed research will investigate the effects on human information processing of certain drugs currently abused. The initial focus will be on barbiturates, amphetamines, and methaqualone, which according to field investigations by our group and others, are extensively abused and frequently associated with serious social problems, especially significant degrees of dependency and markedly disturbed or violent behavior. The techniques used to study these drugs will include behavioral and electrophysiological measures that we have found useful in investigating the effects of marihuana and alcohol on brain functioning. Particular emphasis will be placed on studying components of information processing which may contribute directly or indirectly to repetitive, compulsive drug taking, especially interrelated phenomena of state-dependency, memory storage, and retrieval. Drug-induced alterations in selective attention, decision processes, time-sharing capabilities and memory monitoring processes will also be investigated to ascertain their possible influences on brain mechanisms which underlie deviant behavior that occurs in some settings while individuals are intoxicated by these drugs. Where appropriate, dose-response and time-action relationships will be included.